澳门金沙游戏官网网址是多少:Brain boost

时间:2019-03-07 05:01:00166网络整理admin

By Nell Boyce in Washington DC SUPERSMART mice created by a team of researchers in New Jersey seem to be shedding some light on how memories are recalled in humans. Joe Tsien and his colleagues at Princeton University engineered the mice to test a theory about memories proposed in 1949 by Canadian psychologist Donald Hebb. Hebb argued that when memories form, a cluster of neurons strengthen their connections. When a memory is recalled, the neurons activate simultaneously. So neurons must have a way of “knowing” when others in the cluster are active. Scientists had speculated that this may involve a receptor called NMDA. This will make a neuron fire only if it receives stimuli from two other neurons. Now Tsien and his colleagues have dramatic new proof that NMDA is indeed involved in memory. They genetically altered mice so that they had more versions of a key section of NMDA receptors than usual. Compared with normal mice, the transgenic mice performed much better in several different tests of learning and memory such as in water mazes, object recognition and association of cages or sounds with mild electric shocks on their feet. In some cases, normal mice would retain a memory for only one day while a mutant mouse could remember for five days (Nature, vol 401, p 63). “We were very surprised,” says Ya-Ping Tang, one of the team. He had expected to see some memory improvement, but not on so many diverse tasks. Researchers welcomed the study as strong new support that NMDA plays an important role in memory and learning. “I think this is extremely important. Anything that enhances memory is interesting, and this is such a clear-cut result,” says Eric Kandel of Columbia University in New York, who has studied engineered mice with poor memories. So do the supersmart mice suggest we can improve people’s memories and learning abilities in the same way? Tim Bliss of the National Institute for Medical Research in Mill Hill, London, says there’s no reason to think so. “These are mice that are living a very simple life. You give them a few tests and they do better. It’s science fiction in terms of doing anything with humans,” he argues. “Nobody for a minute would think it would be a good idea to overexpress a gene in a human baby.” But Kandel speculates that studies like this could one day result in treatments for people with impaired memory. “One would ultimately like to be able to improve memory—not to produce superior human beings, but to treat age-related memory loss or mental retardation,